Supplementary Information Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2021		Dec. 31, 2020	Mar. 31, 2020		Dec. 31, 2019
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 2,404		$ 3,526	$ 1,963
Cash, Cash Equivalents and Restricted Cash, Total Company	2,730	[1]	3,873	2,340	[1]	$ 2,173
Other Current Assets [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash	$ 326		$ 347	$ 377

[1] See page 15 for reconciliation of cash and cash equivalents and restricted cash presented in interim Condensed Consolidated Balance Sheets to total cash, cash equivalents and restricted cash presented in the interim Consolidated Statements of Cash Flows.